Earning of 1 worker in 1 day=10800÷(20×6)
Earning of 1 worker in 1 day = Rs. 90
Earning of 20 workers in 1 day=90×20
Earning of 20 workers in 1 day = Rs. 1800
Earning of 20 workers in 8 days=1800×8
Earning of 20 workers in 8 days = Rs. 14400